/Engine/Source/Runtime/NavigationSystem/Public/NavigationSystem.h
Finds random, point in navigable space restricted to Radius around Origin. Resulting location is not tested for reachability from the Origin
true if any location found, false otherwise
bool GetRandomPointInNavigableRadius ( const FVector & Origin, float Radius, [FNavLocation](API\Runtime\Engine\AI\Navigation\FNavLocation) & ResultLocation, [ANavigationData](API\Runtime\NavigationSystem\ANavigationData) * NavData, FSharedConstNavQueryFilter QueryFilter ) const